ASP.NET.in.a.Nutshell.Second.Edition [Electronic resources]

G. andrew Duthie; matthew Macdonald

نسخه متنی -صفحه : 873/ 643
نمايش فراداده

RequiredFieldValidator.NET 1.1, disposable

System.Web.UI.MobileControls (system.web.mobile.dll)class

This class represents a validation control that is used to force user entry in a corresponding input control, like a TextBox. Validation fails if the value in the input control does not differ from the InitialValue property. By default, InitialValue is set to System.String.Empty, and validation will succeed as long as some information has been added to the input control. In this way, the RequiredFieldValidator control works identically to the System.Web.UI.WebControls.RequiredFieldValidator control for full-fledged web pages (although it won't render client-side validation code).

You can use a combination of different validation controls for a single control. For example, you could use a RequiredFieldValidator to ensure that a value is entered, and a RangeValidator to ensure that the value is within a specified data range. This is often required, as validators like RangeValidator will automatically validate a control if it is empty, regardless of the properties you have set.

public class 

RequiredFieldValidator : BaseValidator { // Public Constructors public

RequiredFieldValidator ( ); // Public Instance Properties public string

InitialValue {set; get; } // Protected Instance Methods protected override BaseValidator

CreateWebValidator ( ); // overrides BaseValidator protected override bool

EvaluateIsValid ( ); // overrides BaseValidator }

Hierarchy

System.Object System.Web.UI.Control(System.ComponentModel.IComponent, System.IDisposable, System.Web.UI.IParserAccessor, System.Web.UI.IDataBindingsAccessor) MobileControl(System.Web.UI.IAttributeAccessor) TextControl BaseValidator(System.Web.UI.IValidator) RequiredFieldValidator